Stroboscopic apparatus for calibrating time indicating devices



Jan. 17, 1956 M. WEINBERGER 2,730,890 CALIBRATING J. STROBOSCOPICAPPARATUS FOR TIME INDICATIN EVICES Filed April 1952 United StatesPatent 6 i 2,730,890 Patented Jan. 17, 1956 ice These methods haveproven inadequate in that these devices were inherently inaccurate,diflicult to control and STROBOSCOPIC APPARATUS FOR CALIBRATING TIMEINDICATENG DEVICES Joseph M. Weinberger, Brooklyn, N. 1.

Application April 4, 1952, Serial No. 280,486

5 Claims. (Cl. 73-6) and cumbersome operation.

This invention relates to apparatus for calibrating pre cisioninstruments, and more particularly to calibrating timing instrumentssuch as clocks and watches.

An object of this invention is to provide apparatus of the abovementioned character by means of which the oscillating parts of a watchor clock to be calibrated are stroboscopically compared with similarparts of a standard watch or clock.

Another object of this invention is to provide apparatus which comparesthese oscillating parts by direct observation of the instrument to becalibrated.

A further object of this invention is to provide apparatus whereby theinstrument to be calibrated may be regulated while being intermittentlyilluminated and observed without resorting to phase-shifters and thelike.

A further object is to provide apparatus for calibrating clocks andwatches of an inherent accuracy comparable to the accuracy of theinstrument to be calibrated, without utilizing any external controllingapparatus.

A still further object is to provide apparatus for intermittent views ofsubstantially short duration of alternate half-cycles of oscillation ofthe observed oscillating member of the instrument to be calibrated toeliminate the ambiguous criteria due to apparent displacement of thestroboscopically produced images during successive halfoscillations.

A feature of this invention resides in the manner of intermittentlyilluminating the oscillating member of the instrument to be calibrated.

A further feature of this invention resides in the manner of spacing theintervals of intermittent illumination.

A still further feature of this invention resides in the manner ofavoiding completion of the triggering circuit during alternatehalf-oscillations of the standard oscillating member.

Other objects and features will become apparent from the followingdescriptions and the accompanying drawing in which like numeralsindicate similar parts, and in which:

Fig. l is a diagrammatic view of the mechanical and electrical portionsof an embodiment of this invention,

Fig. 2 is a cross sectional view of the oscillating mechanism and adiagrammatic View of the contacting mechanism, 60

Fig. 3 is an enlarged View of the deflecting wedge showing the positionsof the resilient member during each half-cycle of oscillation, and

Fig. 4 is a schematic view of a circuit adapted to produce intermittentillumination of substantially short duration.

The former practice in watch or clock calibration has been to illuminatethe oscillating parts of these instruments by means of flashing lightscontrolled by means of electronic or rotating mechanical equipment, andthe error determined by means of external devices such as phase-shiftersand the like.

The present invention provides a device of positive operation whereinthe error is observed directly without any ambiguous criteria andimmediately corrected while the timepiece is being observed in thedevice, thus resulting in rapid calibration of the observed instrument.

To properly calibrate a watch or clock of precise manufacture, requiresa standard of equal or higher accuracy against which it can be compared.

This invention provides a device of such accuracy by utilizing theinherent, self-controlled accuracy of an oscillating system, such as abalance wheel of a watch or clock, without resorting to expensive andcumbersome controlling devices and which may be manufactured atsubstantially small cost.

in its simplest embodiment, this invention comprises an oscillatingbalance wheel 1, having a hairspring 2, a roller 3 and a deflectingwedge 4 which is maintained in oscillatory motion by a mainspring andbarrel 5, a gear train 6 and an escapement 7. A pillar plate 8 andbridge 9 support the balance wheel assembly.

The hairspring 2 is attached at one or" its ends to the staff ill of thebalance wheel 1 and, at its other end, to the bridge and is regulated bymeans of a pair of regulator pins iii which restrain the motion of thehairspring.

The deflecting wedge is attached to the roller 3 and subtends asubstantially small angle from the axis of rotation of the balance wheel1'.

Attached to the pillar plate 8 and electrically insulated therefrom bymeans of an insulator block 28 is a resilient member 12 and a contactormember 13, also electrically insulated from the pillar plate 8 and fromthe resilient member 12.

Electrical contact is made with the pillar plate 8 by means ofconnection 14- and with the contactor member 13 by means of connection15.

The source of intermittent illumination shown in this embodiment is aninternally triggered, cold cathode, inert-gas-filled electronic flashlamp 16 which is energized by means of an electronic circuit 17. Thiscircuit is de scribed more particularly hereinbelow.

The connections 14 and 15, and the members 4, 12 and 13, comprise thetriggering mechanism which sets ofi the action of the flash lamp 16 andprovides the intermittent illumination which is directed toward theoscillating member 25 of an instrument to be calibrated.

The mainsprnig 5 is wound up and the balance wheel 1 is caused therebyto be rotated about its axis by means or" the escapement 7, carryingalong with it the deflecting wedge 4, which engages and deflects theresilient member 12 at substantially the time during which the balancewheel l is receiving its impulse from the escapement 7', thus insuring aminimum of interference with the motion of the balance wheel andpromoting greater accuracy of the device.

When the balance wheel 1 is rotating in one direction (i. e., in Fig. 3shown as counter-clockwise) the deflecting wedge 4 causes the resilientmember 12 to assume the position 12a and to deflect toward the contactormember 13, briefly completing the electrical contact from the connection14, through the pillar plate 8, the bridge 9, the hair-spring 2, thedeflecting wedge 4, the resilient member 22, the contactor member 13 andto connection 15, thus triggering a flash of intermittent illuminationof the flash lamp 16, by means of the electronic circuit 17. As thebalance wheel 1 rotates farther, the deflecting wedge 4 releases theresilient member 12, breaking the electrical contact and insuringagainst any spurious and undesired flashes.

When the balance wheel 1 is rotating in the opposite direction (i. e.,clockwise), the deflecting wedge 4 causes the resilient member 12'; toassume position 12b and to deflect away from the contactor member 13,and no elec trical contact is made.

it is to be noted that the deflecting wedge 4 engages the resilientmember 12 at a time when the balance wheel 1 is moving at its greatestangular speed. in this manner, the duration of contact is extremelyshort and the instant of flash is accurately determined. This obviatesthe possibility of spurious flashes which would make a device of thiskind diflicult, if not impossible, to use as an accurate calibratingdevice.

Thus, the electrical circuit is completed during alter nate half-cyclesof oscillation of the balance wheel 1, when it is rotating in acounter-clockwise direction.

in 4, an electronic circuit is shown which comprises a voltage doublercircuit having rectifiers l8 and condensers i9, charging circuit havinga condenser 20, a resistor 26 and a voltage divider 21, an internallytriggercd, cold cathode, inert-gas-fllled flash lamp 16 and a triggeringcircuit having resistors 22 and 23 and condenser 24. Connections 14 anare connected respectively to the pillar plate 8 and the contactormember 13 as hereinbefore described.

The flash lamp 16 flashes at a rate determined by the period ofoscillation of the balance wheel 1 and intermittently illuminates theoscillating member 25 of an instrument to be calibrated, which is vieweddirectly or through an optical system 27.

When the oscillating member 25 is synchronized with the balance wheel 1,it will appear to remain substantially stationary, while being observedunder the intermittent illumination of the flash lamp 16. An apparentrotation of the oscillating member 25 in either direction indicates anout of synchronism condition which is rapidly corrected by means of theregulator provided in the instrument to be calibrated, which is adjusteduntil the apparent rotation has stopped.

Many mechanical faults of the instrument to be calibrated can bediagnosed by observing the characteristics of the apparent rotation ofthe oscillating member 25.

A set of indicating hands moving at different speeds may be attached tothe gear train to check the accuracy of the standard instrument on acalibrated dial 29 by observing the positions of the said hands andcomparing them with another timepiece.

in other embodiments of this invention, the escapement 7 and theoscillating assembly may be driven directly by a mainspring or othersource of rotary power without the use of intermediate gears.

The deflecting wedge 4 may be attached to any part of the balance Wheelassembly or may be made integral therewith. I

I wish it distinctly understood that, while I have particularlydescribed the simplest elements adapted to perform the functions setforth, it is obvious that they could be subject to modifications, andvarious changes in form, proportion and in minor details of constructionmay be resorted to without departing from the spirit or sacrificing anyof the principles of the invention.

What I claim is:

1. An apparatus for calibrating time indicating devices comprising anoscillating member, a flash lamp for intermittently illuminating aninstrument to be calibrated, a circuit for momentarily energizing saidflash lamp, a defleeting wedge electrically connected to and moving withsaid oscillating member and comprising one leg of a trigger circuit ofsaid flash lamp energizing circuit, a resilient member adjacent saidoscillating member, and a contactor member adjacent said resilientmember and comprising the other leg of said trigger circuit; saidresilient member and said contactor member normally forming part of anopen circuit; said deflecting wedge positioned to engage said resilientmember in substantially a period of maximum angular speed of saidoscillating member and adapted to deflect said resilient member awayfrom said contactor member during one half-cycle and to deflect saidresilient member to momentarily touch said contactor member during apredetermined angular displacement of said oscillating member in theother halfcycle of oscillation of said oscillating member to close thesaid trigger circuit in response to said alternate halfcycles ofoscillation and to disengage said resilient member after saidpredetermined angular displacement to break electrical contact betweensaid wedge and said resilient member before electrical contact is brokenbetween said resilient member and said contactor member.

2. An apparatus for calibrating time indicating devices comprising anoscillating member, spring means for storing power to impart oscillatorymotion thereto, a flash lamp for intermittently illuminating aninstrument to be calibrated, a circuit for momentarily energizing saidflash lamp, a deflecting wedge electrically connected to and moving atthe same speed as said oscillating member and comprising one leg of atrigger circuit of said flash lamp energizing circuit, a resilientmember adjacent said oscillating member, and a contactor member adjacentsaid resilient member and comprising the other leg of said triggercircuit; said resilient member and said contactor member normallyforming part of an open circuit; said deflecting wedge disposed toengage said resilient member in substantially a period of maximumangular speed of said oscillating member and adapted to deflect saidresilient member to touch said contactor member during a predeterminedangular displacement of said oscillating member in alternate half-cyclesof oscillations of said oscillating member and close the said triggercircuit in response to said alternate half-cycles of oscillation and todis engage said resilient member after said predetermined angulardisplacement to break electrical contact between said wedge and saidresilient member before electrical contact is broken between saidresilient member and said contactor member.

3. An apparatus for calibrating time indicating devices comprising anoscillating member, spring means for storing power to impart oscillatorymotion thereto, speed reducing means and escapement means to cooperatewith said oscillating member to impart oscillatory motion thereto, aflash lamp for intermittently illuminating an instrument to becalibrated, a circuit for momentarily energizing said flash lamp, adeflecting wedge electrically connected to and moving with the samespeed as said oscillating member and comprising one leg of a triggercircuit of said flash lamp energizing circuit, a resilient memberadjacent said oscillating member, and a contactor member adjacent saidresilient member and comprising the other leg of said trigger circuit;said resilient member and said contactor member normally forming part ofan open circuit; said deflecting wedge disposed to engage said resilientmember in substantially a period of maximum angular speed of saidoscillating member and adapted to deflect said resilient member to touchsaid contactor member during a predetermined angular displacement ofsaid oscillating member in alternate haltcycles of oscillation of saidoscillating member and close the trigger circuit of said flash lampenergizing circuit in response to said alternate half-cycles ofoscillation and to disengage said resilient member after said angulardis placement to break electrical contact between said wedge and saidresilient member before electrical contact in broken between saidresilient member and said contactor member.

4. In an apparatus for calibrating time indicating devices, anoscillating member, a deflecting wedge attached and electricallyconnected thereto and comprising one leg of a trigger circuit of a flashlamp energizing circuit, a resilient member adjacent said oscillatingmember, and a contactor member adjacent said resilient member andcomprising the other leg of said trigger circuit; said resilient memberand said contactor member normally forming part of an open circuit; saiddeflecting wedge disposed to engage said resilient member in a period ofsubstantially maximum angular speed of said oscillating member andadapted to deflect said resilient member away from said contactor memberduring one halfcycle and to deflect said resilient member to momentarilytouch said contactor member during a predetermined angular displacementof said oscillating member in the other half-cycle of oscillation ofsaid oscillating member to complete the said trigger circuit from saidoscillating member through said wedge, said resilient member and saidcontactor member to trigger said flash lamp energizing circuit andmomentarily illuminate an instrument to be calibrated in response tosaid alternate halfcycles of oscillation and to break the electricalcircuit between said wedge and said resilient member after saidpredetermined angular displacement of said oscillating member beforeelectrical contact is broken between said resilient member and saidcontactor member.

5. In an apparatus for calibrating time indicating devices, anoscillating member, spring means for storing power to impart oscillatorymotion thereto, a deflecting wedge attached and electrically connectedto said oscillating member and comprising one leg of a trigger circuitof a flash lamp energizing circuit, a resilient member adjacent saidoscillating member, and a contactor member adjacent said resilientmember and comprising the other leg of said trigger circuit; saidresilient member and said contactor member normally forming part of anopen circuit; said deflecting wedge disposed to engage said resilientmember in a period of maximum angular speed. of said oscillating memberand adapted to deflect said resilient member to momentarily touch saidcontactor member during a predetermined angular displacement of saidoscillating member in alternate half-cycles of 05 cillation of saidoscillating member and close a trigger circuit of a flash lampenergizing circuit from said oscillating member through said wedge, saidresilient member and said contactor member and momentarily illuminate aninstrument to be calibrated in response to said alternate half-cycles ofoscillation and to break the electrical circuit between said wedge andsaid resilient member after said predetermined angular displacement ofsaid oscillating member before electrical contact is broken between saidresilient member and said contactor member.

References Cited in the file of this patent UNITED STATES PATENTS2,037,161 Fetter et al Apr. 14, 1936 2,108,010 Delviniotti Feb. 8, 19382,143,074 Killrnan et al. Jan. 10, 1939 2,183,655 Morton Dec. 19, 19392,444,178 Weinberger June 29, 1948 2,454,983 Weinberger Nov. 30, 19482,587,452 Farris Feb. 26, 1952

